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                    计算机基础-操作系统-进程-计算机网络
            
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                    volatile&synchronized
            
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                    object/wait/notify
            
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                    thread
            
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                    线程池的工作原理
            
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                    lock&ReentrantLock&ReadWriteLock
            
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                    lock&condition
            
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                    Java并发工具- CountDownLatch&CyclicBarrier 
            
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                    Java同步工具类- CountDownLatch&CyclicBarrier&Semaphore  
            
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                    java8新语法-Stream-分组groupingBy操作 
            
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                    SpringBoot
            
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                    SpringBoot项目启动脚本
            
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                    mybatis中操作元数据
            
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                    mybatis中insert/update/delete标签中执行多条SQL语句
            
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                    【分布式】sharding-jdbc实现分库分表
            
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                    SQL常用使用
            
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                    redis学习笔记
            
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                    Redis中的队列list实现秒杀活动抢购
            
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                    mysql绿色版安装服务教程
            
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                    缓存
            
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                    MySQL单表备份还原
            
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                    web简单积累
            
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                    linux常用命令
            
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                    windows常用命令
            
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                    maven引入依赖时识别不到本地仓库的jar
            
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                    spring security 配置发生错误 Can't configure antMatchers after anyRequest
            
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                    AOP内获取了对请求流操作后报流已经关闭错误的问题
            
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        <li class="chapter " data-level="26.1" data-path="../tools/github/github_ssh.html">
            
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                    Github ssh key 解决提交后push频繁输入用户名和密码
            
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                    sharding-jdbc-4.1.1版本启动数据源报错问题
            
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<p>   Java&#x4E2D;switch&#x652F;&#x6301;char\int\byte\short&#x53CA;&#x5B83;&#x4EEC;&#x7684;&#x5C01;&#x88C5;&#x7C7B;&#x7C7B;&#x578B;&#xFF0C;&#x8FD8;&#x6709;&#x679A;&#x4E3E;&#x7C7B;&#x578B;&#x3002;   </p>
<p>&#x200B;    Java7&#x4E2D;&#x989D;&#x5916;&#x65B0;&#x589E;&#x4E86;String&#x7C7B;&#x578B;&#xFF0C;&#x8FD9;&#x4E2A;&#x65B0;&#x7279;&#x6027;&#x662F;&#x7F16;&#x8BD1;&#x5668;&#x8FD9;&#x4E2A;&#x5C42;&#x6B21;&#x5B9E;&#x73B0;&#x7684;&#x3002;&#x800C;&#x5728;&#x865A;&#x62DF;&#x673A;&#x548C;&#x5B57;&#x8282;&#x4EE3;&#x7801;&#x5C42;&#x6B21;&#x4E0B;&#xFF0C;&#x8FD8;&#x662F;&#x53EA;&#x652F;&#x6301;&#x4F7F;&#x7528;&#x4E0E;&#x6574;&#x6570;&#x7C7B;&#x578B;&#x517C;&#x5BB9;&#x7684;&#x7C7B;&#x578B;&#x3002;</p>
<p>&#x200B;    <strong>&#x867D;&#x7136;&#x5F00;&#x53D1;&#x4EBA;&#x5458;&#x5728;java&#x6E90;&#x4EE3;&#x7801;&#x4E2D;&#x4F7F;&#x7528;&#x7684;&#x662F;String&#x7C7B;&#x578B;&#xFF0C;&#x4F46;&#x662F;&#x5728;&#x7F16;&#x8BD1;&#x8FC7;&#x7A0B;&#x4E2D;&#xFF0C;&#x662F;&#x5C06;String&#x7C7B;&#x578B;&#x66FF;&#x6362;&#x6210;&#x5BF9;&#x5E94;&#x7684;hashcode&#xFF0C;&#x800C;case&#x91CC;&#x9762;&#x7684;&#x503C;&#x4E5F;&#x88AB;&#x66FF;&#x6362;&#x6210;&#x5E38;&#x91CF;&#x7684;&#x54C8;&#x5E0C;&#x503C;&#xFF0C;&#x7136;&#x540E;&#x518D;case&#x8BED;&#x53E5;&#x4E2D;&#x4ECD;&#x7136;&#x8981;&#x4F7F;&#x7528;String&#x7684;equals&#x65B9;&#x6CD5;&#x6765;&#x8FDB;&#x884C;&#x5B57;&#x7B26;&#x4E32;&#x7684;&#x5224;&#x65AD;&#x3002;</strong>   </p>
<p>&#x5982;: Java&#x6E90;&#x4EE3;&#x7801;</p>
<pre><code class="lang-java"><span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">xx</span><span class="hljs-params">(String key)</span></span>{
        String sigal = <span class="hljs-string">&quot;&quot;</span> ;
        <span class="hljs-keyword">switch</span> (key) {
        <span class="hljs-keyword">case</span> <span class="hljs-string">&quot;&#x5927;&#x4E8E;&quot;</span>:
            sigal = <span class="hljs-string">&quot;&#x5927;&#x4E8E; &gt; &quot;</span> ;
            <span class="hljs-keyword">break</span>;
        <span class="hljs-keyword">case</span> <span class="hljs-string">&quot;&#x5C0F;&#x4E8E;&quot;</span>:
            sigal = <span class="hljs-string">&quot;&#x5C0F;&#x4E8E; &gt; &quot;</span> ;
            <span class="hljs-keyword">break</span>;
        <span class="hljs-keyword">case</span> <span class="hljs-string">&quot;&#x7B49;&#x4E8E;&quot;</span>:
            sigal = <span class="hljs-string">&quot;&#x7B49;&#x4E8E; &gt; &quot;</span> ;
            <span class="hljs-keyword">break</span>;
        <span class="hljs-keyword">default</span>:
            sigal = <span class="hljs-string">&quot; &#x9519;&#x8BEF; &quot;</span> ;
            <span class="hljs-keyword">break</span>;
        }
        System.out.println(sigal);
    }
</code></pre>
<p>&#x7F16;&#x8BD1;&#x540E;</p>
<pre><code class="lang-java"><span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">xx</span><span class="hljs-params">(String key)</span> </span>{
      String sigal;
      label23: {
         sigal = <span class="hljs-string">&quot;&quot;</span>;
         <span class="hljs-keyword">switch</span>(key.hashCode()) {
         <span class="hljs-keyword">case</span> <span class="hljs-number">727623</span>:
            <span class="hljs-keyword">if</span>(key.equals(<span class="hljs-string">&quot;&#x5927;&#x4E8E;&quot;</span>)) {
               sigal = <span class="hljs-string">&quot;&#x5927;&#x4E8E; &gt; &quot;</span>;
               <span class="hljs-keyword">break</span> label23;
            }
            <span class="hljs-keyword">break</span>;
         <span class="hljs-keyword">case</span> <span class="hljs-number">750687</span>:
            <span class="hljs-keyword">if</span>(key.equals(<span class="hljs-string">&quot;&#x5C0F;&#x4E8E;&quot;</span>)) {
               sigal = <span class="hljs-string">&quot;&#x5C0F;&#x4E8E; &gt; &quot;</span>;
               <span class="hljs-keyword">break</span> label23;
            }
            <span class="hljs-keyword">break</span>;
         <span class="hljs-keyword">case</span> <span class="hljs-number">998501</span>:
            <span class="hljs-keyword">if</span>(key.equals(<span class="hljs-string">&quot;&#x7B49;&#x4E8E;&quot;</span>)) {
               sigal = <span class="hljs-string">&quot;&#x7B49;&#x4E8E; &gt; &quot;</span>;
               <span class="hljs-keyword">break</span> label23;
            }
         }
         sigal = <span class="hljs-string">&quot; &#x9519;&#x8BEF; &quot;</span>;
      }
      System.out.println(sigal);
   }
</code></pre>
<h4 id="twr"><a name="twr" class="anchor-navigation-ex-anchor" href="#twr"><i class="fa fa-link" aria-hidden="true"></i></a><strong>TWR</strong></h4>
<p>   <strong>TWR:</strong>   try-with-resources&#xFF0C;&#x80FD;&#x591F;&#x88AB;try&#x8BED;&#x53E5;&#x6240;&#x7BA1;&#x7406;&#x7684;&#x8D44;&#x6E90;&#x9700;&#x8981;&#x6EE1;&#x8DB3;&#x4E00;&#x4E2A;&#x6761;&#x4EF6;&#xFF0C;&#x5C31;&#x662F;&#x5176;&#x8D44;&#x6E90;java&#x7C7B;&#x8981;&#x5B9E;&#x73B0;<strong>AutoCloseable</strong>&#x63A5;&#x53E3;&#xFF0C;&#x5426;&#x5219;&#x4F1A;&#x51FA;&#x73B0;&#x7F16;&#x8BD1;&#x9519;&#x8BEF;&#x3002;</p>
<p>&#x5F53;&#x9700;&#x8981;&#x91CA;&#x653E;&#x8D44;&#x6E90;&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x8BE5;&#x63A5;&#x53E3;&#x7684;close&#x65B9;&#x6CD5;&#x4F1A;&#x88AB;&#x81EA;&#x52A8;&#x8C03;&#x7528;&#x3002;   </p>
<p>&#x4EE3;&#x7801;</p>
<pre><code class="lang-java"><span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">twr</span><span class="hljs-params">()</span></span>{
    <span class="hljs-comment">// &#x53EF;&#x81EA;&#x52A8;&#x5173;&#x95ED;</span>
    <span class="hljs-keyword">try</span>(FileInputStream in = <span class="hljs-keyword">new</span> FileInputStream(<span class="hljs-string">&quot;e:\\fstab&quot;</span>);
            FileOutputStream out = <span class="hljs-keyword">new</span> FileOutputStream(<span class="hljs-string">&quot;e:\\a&quot;</span>);){
        <span class="hljs-keyword">byte</span>[] buffer = <span class="hljs-keyword">new</span> <span class="hljs-keyword">byte</span>[<span class="hljs-number">1024</span>];
        <span class="hljs-keyword">int</span> len = -<span class="hljs-number">1</span> ;
        <span class="hljs-keyword">while</span> ((len = in.read(buffer)) != -<span class="hljs-number">1</span>) {
            out.write(buffer, <span class="hljs-number">0</span>, len);
        }
    } <span class="hljs-keyword">catch</span> (Exception e) {
        e.printStackTrace();
    }
}
</code></pre>
<h4 id="objects"><a name="objects" class="anchor-navigation-ex-anchor" href="#objects"><i class="fa fa-link" aria-hidden="true"></i></a><strong>Objects</strong></h4>
<p>   &#x5728;java.util&#x5305;&#x4E2D;&#x65B0;&#x589E;&#x4E86;&#x4E00;&#x4E2A;&#x7528;&#x6765;&#x64CD;&#x4F5C;&#x5BF9;&#x8C61;&#x7684;&#x5DE5;&#x5177;&#x7C7B;java.util.Objects&#x3002;</p>
<p><strong>Objects</strong>&#x7C7B;&#x4E2D;&#x5305;&#x542B;&#x7684;&#x90FD;&#x662F;&#x9759;&#x6001;&#x65B9;&#x6CD5;&#xFF0C;&#x53EF;&#x8FDB;&#x884C;&#x5FEB;&#x901F;&#x5BF9;&#x5BF9;&#x8C61;&#x64CD;&#x4F5C;&#x3002;   </p>
<p>&#x200B;    <strong>compare</strong>&#x65B9;&#x6CD5;:&#x4E24;&#x5BF9;&#x8C61;&#x6BD4;&#x8F83;&#x64CD;&#x4F5C;&#x3002;   </p>
<p>&#x200B;    <strong>equals</strong>&#x65B9;&#x6CD5;:&#x5224;&#x65AD;&#x4E24;&#x4E2A;&#x5BF9;&#x8C61;&#x662F;&#x5426;&#x76F8;&#x7B49;&#xFF0C;&#x82E5;&#x4E24;&#x4E2A;&#x90FD;&#x662F;null&#xFF0C;&#x5219;&#x4E3A;true&#xFF1B;&#x82E5;&#x4E00;&#x4E2A;&#x4E3A;&#x7A7A;&#xFF0C;&#x5219;&#x4E3A;false   </p>
<p>&#x200B;    <strong>deepEquals</strong>&#x65B9;&#x6CD5;:&#x4F5C;&#x7528;&#x4E8E;equals&#x76F8;&#x4F3C;&#xFF0C;&#x82E5;&#x53C2;&#x6570;&#x662F;&#x6570;&#x7EC4;&#xFF0C;&#x5219;&#x8C03;&#x7528;Arrays&#x7C7B;&#x7684;deepEquals&#x8FDB;&#x884C;&#x6570;&#x7EC4;&#x6BD4;&#x8F83;   </p>
<p>&#x200B;    <strong>toString</strong>&#x65B9;&#x6CD5;:&#x83B7;&#x53D6;&#x5BF9;&#x8C61;&#x5B57;&#x7B26;&#x4E32;&#x5F62;&#x5F0F;&#xFF0C;&#x82E5;&#x53C2;&#x6570;&#x4E3A;null&#xFF0C;&#x5219;&#x8F93;&#x51FA;null&#x5B57;&#x7B26;&#x4E32;&#x3002;&#x5F53;&#x4F20;&#x5165;&#x53C2;&#x6570;&#x662F;&#x4E24;&#x4E2A;&#x65F6;&#xFF0C;&#x5982;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x4E3A;null&#xFF0C;&#x5219;&#x8F93;&#x51FA;&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x5F53;&#x4F5C;&#x8FD4;&#x56DE;&#x503C;(&#x76F8;&#x5F53;&#x4E8E;&#x9ED8;&#x8BA4;&#x503C;)   </p>
<pre><code class="lang-java"><span class="hljs-meta">@Test</span>
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">objects</span><span class="hljs-params">()</span></span>{

    <span class="hljs-comment">// &#x5224;&#x65AD;&#x4E24;&#x4E2A;&#x5BF9;&#x8C61;&#x662F;&#x5426;&#x76F8;&#x7B49;&#xFF0C;&#x5982;&#x6709;&#x4E00;&#x4E2A;&#x4E3A;null&#xFF0C;&#x5219;&#x4E3A;false</span>
    <span class="hljs-keyword">boolean</span> equals = Objects.equals(<span class="hljs-string">&quot;a&quot;</span>, <span class="hljs-keyword">new</span> String(<span class="hljs-string">&quot;a&quot;</span>)); <span class="hljs-comment">// true</span>
    <span class="hljs-keyword">boolean</span> equals1 = Objects.equals(<span class="hljs-keyword">null</span>, <span class="hljs-keyword">new</span> String(<span class="hljs-string">&quot;a&quot;</span>)); <span class="hljs-comment">// false</span>
    <span class="hljs-comment">// &#x6570;&#x7EC4;&#x6BD4;&#x8F83;</span>
    <span class="hljs-keyword">boolean</span> equals2 = Objects.deepEquals(<span class="hljs-keyword">new</span> String[]{<span class="hljs-string">&quot;a&quot;</span>,<span class="hljs-string">&quot;b&quot;</span>}, <span class="hljs-keyword">new</span> String[]{<span class="hljs-string">&quot;a&quot;</span>,<span class="hljs-string">&quot;b&quot;</span>}); <span class="hljs-comment">// true</span>
    <span class="hljs-comment">// &#x83B7;&#x53D6;&#x5BF9;&#x8C61;&#x5B57;&#x7B26;&#x4E32;&#x5F62;&#x5F0F;</span>
    String str = Objects.toString(<span class="hljs-keyword">null</span>,<span class="hljs-string">&quot;&#x53C2;&#x6570;&#x4E3A;&#x7A7A;&quot;</span>); <span class="hljs-comment">// &#x8F93;&#x51FA; &#x201C;&#x53C2;&#x6570;&#x4E3A;&#x7A7A;&#x201D;</span>
}
</code></pre>
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